School of Chemistry and Environmental Science, Henan Normal University, Xinxiang, Henan 453007, PR China.
J Pharm Biomed Anal. 2011 Sep 10;56(2):336-42. doi: 10.1016/j.jpba.2011.05.018. Epub 2011 May 20.
In this study, the binding mode of phloridzin with human serum albumin (HSA) was established under physiological condition. The binding study is important to understand the pharmacokinetics and toxicity of phloridzin. The results proved the mechanism of fluorescence quenching of HSA by phloridzin was due to the formation of HSA-phloridzin complex. The binding constants, the number of binding sites and thermodynamic parameters were calculated. In addition, the alterations of HSA secondary structure in the presence of phloridzin were confirmed by the evidences from Fourier transform infrared (FT-IR), UV-visible absorption, circular dichroism (CD), synchronous and three-dimensional fluorescence spectroscopy. Alterations of protein conformation were observed with reduction of α-helix from 54% (free HSA) to 50% in the HSA-phloridzin complexes, indicating a partial protein unfolding. The distance between phloridzin and HSA was 3.74 nm according to fluorescence resonance energy transfer theory. In addition, the effects of common ions on the constants of HSA-phloridzin complex were also discussed.
在这项研究中，建立了根皮苷与人血清白蛋白（HSA）在生理条件下的结合模式。结合研究对于了解根皮苷的药代动力学和毒性非常重要。结果证明，根皮苷荧光猝灭 HSA 的机制是由于形成了 HSA-根皮苷复合物。计算了结合常数、结合位点数和热力学参数。此外，通过傅里叶变换红外（FT-IR）、紫外-可见吸收、圆二色性（CD）、同步和三维荧光光谱的证据，证实了根皮苷存在时 HSA 二级结构的变化。与游离 HSA 相比（54%），HSA-根皮苷复合物中α-螺旋减少到 50%，表明蛋白质部分展开。根据荧光共振能量转移理论，根皮苷与 HSA 之间的距离为 3.74nm。此外，还讨论了常见离子对 HSA-根皮苷配合物常数的影响。
